Wireless access systems have been widely deployed to provide various types of communication services such as voice or data. In general, a wireless access system is a multiple access system that supports communication of multiple users by sharing available system resources (a bandwidth, transmission power, etc.) among them. For example, multiple access systems include a Code Division Multiple Access (CDMA) system, a Frequency Division Multiple Access (FDMA) system, a Time Division Multiple Access (TDMA) system, an Orthogonal Frequency Division Multiple Access (OFDMA) system, and a Single Carrier Frequency Division Multiple Access (SC-FDMA) system.
Recently, due to entry into a hyper-connected society and appearance of big data accompanied with the development of new paradigms of mobile smart devices and services, mobile traffic has doubled every year. The communication business expects that the mobile traffic will be increased more than 1000 times in ten years. In addition, the rapidly increased mobile traffic may also increase the burden of mobile network providers. However, improvement of traffic capacity required to cope with the excessively increased mobile traffic cannot be achieved in the conventional mobile communication system where acquisition of additional frequency resources is limited. Therefore, 5G mobile communication technology based on the millimeter wave needs to be developed to secure broad bandwidth.